Nuclear reactor (illustration)
Nuclear reactor (illustration) Flash 90

Unknown assailants killed five nuclear engineers on Sunday while they were on a bus just north of Damascus near the research center where they worked, AFP reported on Sunday.

The Britain-based Syrian Observatory for Human Rights, which relies on a network of sources on the ground for its reports, later told AFP four of the engineers were Syrian, while one was Iranian.

"Unidentified attackers murdered five nuclear energy engineers who worked in the scientific research centre near the neighborhood of Barzeh, northern Damascus," said Observatory director Rami Abdel Rahman, according to the report.

He later said, "Four of the engineers were Syrian, and one was Iranian. Their bus was ambushed while they were on their way to the research centre. Their assailants shot them dead."

In July last year, six people who worked at the same center were killed in a mortar attack carried out by rebels seeking President Bashar Al-Assad's ouster, noted AFP.

Another military research center, also near Damascus, was also hit by an airstrike in May of 2013, which the Syrian foreign ministry had blamed on Israel.